New to me 3GMF with some questions

[RGBrogan]

Hello all,

I have been lurking around here for some time, it is amazing all the knowledge I was able to gain by reading all the postings and searching for topics. From everything I learned here I felt comfortable in moving up from my O'day 26 to an H34. Also thanks to all the posters about the H34 compression post issue, I made sure to check that out first thing and I don't seem to have that issue, all of your postings were big help.

Anyway, I purchased the new to me 1985 Hunter 34 back in October, it was on the hard for so it has been a long winter while I wait to take it out. It has a Yanmar 3GMF with 850ish hours and I have a few questions, the whole engine thing is new to me and I want to learn as much as possible. It started up within 5 to 10 seconds when I had it surveyed the surveyor said, most major issues with a diesel you will know from how it starts up, runs and idles. It started up without complaints and ran and idled well, so the surveyor seemed comfortable in saying the engine was in good condition. I was able to run it with the cooling line attached to a hose several times in the fall, and I had no problems. So last weekend we took it out for the first time, very exciting, and we ran into some weather on the way back and had to motor for about 2 hrs. I made sure to not exceed 3000 RPM as I did not want to push the engine too much incase Murphy decided to show up. The next day I took the boat over to the fuel dock for a top off and pump out, the motor started within 10 seconds and everything seemed fine. I go to the boat last night to check all the fluids and to my shock I find evidence of Murphy's visit, the coolant reservoir was empty, and there did not seem to be much coolant when I took the radiator cap off. I made sure the coolant tank was filled with green coolant before we took her out. I also discovered I need to repack the gland as it is leaking two drips per second.

Here are my questions, with the most concerning to me first.

I did not smell anything, nor did I see any smoke, no alarms went off, and there does not seem to be any water in the oil, at least from looking at the dipstick, and the engage starts up just fine still, what possible damage could I have done if it ran without coolant?

How true is the statement that you can get an idea of problems by how easily the diesel starts and idles?

What mixture should I ensure to antifreeze and water for the freshwater cooling?

I have and am familiar with a volt meter, so how do I know or test that the engine overheat alarm is still functioning?

The PO installed a coolant temp gauge, which I don’t think works, with said volt meter how can I test that the senders are working or need to be replaced?

Since I am getting water in the bilge from the packing glad, is there a quick way to tell if the coolant leaked into the bilge? (and no I don't want to taste the bilge water to see if it tastes sweet )

I hope to fill up the coolant tank tonight and attempt to spot the leak, if it is not as simple as a hose clamp, and I am not sure if the coolant leaked into the bilge, could the coolant somehow mix with the raw water and go out through the exhaust?

Is it possible that the coolant leaked into the hot water tank?

Thanks for all the responses in advance. Hopefully the problem will be something small and I haven't bit off more than I can chew.

[JohnRPollard]

Hi RGB, welcome to Sailnet!

First, don't panic about the engine. Your coolant level may be lower than is optimal, but I doubt you overheated your engine or did damage.

You don't say where your boat is located. The first question that comes to mind is whether it was properly winterized? Maybe you don't need to winterize where you sail?

Just some thoughts/observations (hopefully others will chime in as well):

The coolant "reservoir" that you mentioned is really more of an expansion tank. In many instances, these are not installed at the correct height relative to the heat exchanger, so can empty or overfill depending whether mounted too high or too low. So that is one thing to consider.

Consult your engine owner's manual to determine what coolant mixture is best for your climate. If you do not have the engine manual, it is well worth the cost of buying one.

I doubt the water in the bilge is engine coolant. If you do have a leak in the cooling system and you can't see any apparent source of the leak, it is probably in the heat exchanger, in which case the coolant is being dumped overboard with the raw water.

It's unlikely but not impossible that the coolant leaked into the hot water tank. But you'd find out immediately when you used the hot water -- it would be contaminated.

Your stuffing box may or may not need repacking. Start by tightening the packing nuts. There's a good chance this will reduce the drip significantly (but don't over tighten either).

[arf145]

I'm with John. Seems unlikely you've done any harm. I'm not even sure there's a problem. Being a little low on coolant when it's cold isn't the same as being out of coolant. Add a little, per your manual.

Don't know about the idle test, but it doesn't sound entirely unreasonable. We used a version of this test when we purchased our boat with a 20-something year old Yanmar: does it start easily and idle and run at cruising speed without smoke.

[Faster]

FWIW we had a heat exchanger leak last summer and it turned out that the RW pressure was higher than the FWC pressure and RW leaked into the FW side, overfilling the expansion tank.

I was led to believe that's typical of the pressure relationship in a FWC engine.

If you have a leak in the HW tank circuit, unless you're running the tap there's really nowhere for that water to go - it would be a dead end.

So if indeed you're losing coolant it's likely from the seal on the FWC pump or a hose clamp/connection somewhere. The coolant should be evident in the engine sump or bilge, where ever that leak could get to.

It's possible you don't have a problem at all, beyond a leaking packing gland.

[RGBrogan]

All,

Thank you very much for your responses. I keep the boat in New Jersey on the Raritan bay.
I found some answers for my questions by downloading a manual at: www.motoren.ath.cx/menus/yanmar.html.

The info in the documentation covered my questions about the senders. I just now need time to test them, pesky work keeps getting in the way! I went back to the boat last night, filled up the engine with coolant and ran it for a bit. I think there may not have been enough coolant in the heat exchanger, it says the 3GMF takes about a gallon of coolant. Previously I filled it until it reached the top of the heat exchanger, then last night I put another half gallon of coolant in. I ran it and I didn’t see any coolant leaks, so we will see what happens. However I did find 2 other leaks. The fuel filter was leaking and the raw water pump was leaking. I figure since I have no idea when the last time these were changed, along with the oil, it would be a good time to change these. When I get everything back together hopefully there will be no leaks. Once again, thanks for the help guys.